Mechanical watch movement

ABSTRACT

A mechanical watch movement comprising a minute-wheel and pinion, a cannon pinion with a toothing which meshes with that of the minute-wheel and an hour-wheel coaxial with the cannon-pinion and cooperating with the minute-wheel pinion, wherein the minutewheel pinion is thicker than the minute-wheel, the minute-wheel pinion further comprises teeth each having for at least a portion of its thickness a lateral face in the form of an arc of a cylinder coaxial with the minute-wheel pinion whereas some of the teeth each have a point extending beyond the lateral face, said lateral face thus being thinner than the minute-wheel pinion, the minute-wheel is driven onto the lateral faces and the outside diameter of the toothing of the hour-wheel is such that only the points cooperate with the hour-wheel toothing.

United States Patent I191 Bachmann June 10, 1975 I l MECHANICAL WATCHMOVEMENT Peter Baclimann. Bcttlach, Switzerland 22 Filed: Apr. 29, 1974211 Appl. No; 465,077

[75} Inventor:

FOREIGN PATENTS OR APPLICATIONS United Kingdom 58/l39 PrimaryE.taminerGeorge H. Miller, Jr. Attorney Agent, or FirmStevens, Davis,Miller & Mosher I ABSTRACT A mechanical watch movement comprising aminute wheel and pinion, a cannon pinion with a toothing which mesheswith that of the minute-wheel and an hour-wheel coaxial with thecannon-pinion and cooperating with the minute-wheel pinion, wherein theminutewheel pinion is thicker than the minute-wheel, the minute-wheelpinion further comprises teeth each having for at least a portion of itsthickness a lateral face in the form of an arc of a cylinder coaxialwith the minute-wheel pinion whereas some of the teeth each have a pointextending beyond the lateral face said lateral face thus being thinnerthan the minutewheel pinion, the minute-wheel is driven onto the lateralfaces and the outside diameter of the toothing of the hour-whee] is suchthat only the points cooperate with the hour-wheel toothing.

5 Claims, 4 Drawing Figures PATENTEDJUMO m5 3.888.077 SHEET 1 FIG 1PATENTEDJUH10|915 3,888,077

SHEET 2 FIG. 2

SHEET PATENTEDJUH 10 I975 7/ //////////fi/// M S M EC HAN [C AL W ATL HMOV EM ENT This invention relates to a mechanical watch niovementcomprising a minute-wheel and pinion. a cannonpinion with a toothingwhich meshes with that of the minute-wheel. and an hour wheel coaxialwith the cannon-pinion and coperating with the minute-wheel pinion.

In conventional mechanical watch movements. the cannon-pinion bears aminute-hand at the end of its pipe, while the hour-wheel itself bears anhour-hand. The pipe of the cannon-pinion and that of the hourwheel passthrough a central opening in the dial. the latter being placed directlyagainst the outer face of the base plate. In order for the cannon-pinionto rotate at the rate of one revolution per hour. and the hour-wheel atthe rate of one revolution every 12 hours. the reduction ratios betweenthe cannon-pinion and the minute wheel on the one hand. and between thecannon-pinion and the minute-wheel on the one hand, and between theminute-wheel pinion and the hour-wheel on the other hand. must he suchthat their product equals 12. in certain known movements of this type.the minutewheel and pinion constitute the driving members of thedial-train; and when the minute-wheel and pinion are directly coupled tothe barrel-drum. the movement must be designed in such a way that thebarrel-drum rotates at a speed determined by the said reduction ratios.

Watch movements are also known in which the cannon-pinion and thehour-wheel carry discs entirely cov ered by the dial. These discs bearminuteand hourindications which appear in an aperture in the dial. Inmovements of this type. the hour-wheel is generally driven by jumps ofone-twelfth of a revolution per hour, whereas the cannon-pinion isdriven in continuous mo tion.

The minute-wheel and pinion of mechanical watch movements often comprisea pinion which is thicker than the wheel, the latter being driven onto acylindrical bearing surface produced by lathe-turning on a portion ofthe thickness of the pinion. Thus the teeth of the pinion areeliminated, and its hub is reduced in diameter for as much of itsthickness as is necessary for driving on the minute-wheel. When theminute-wheel and pinion are intended to drive a jumping hour-wheel. onthe other hand. different designs are used. with the minute-wheel andpinion comprising a twoor three-tooth star in the center.

it is the object of the present invention to provide for more efficientmass-production of watch movements. A more particular object is toenable the production of both movements with hourand minute-hands andmovements equipped with hourand minute-indicating discs starting fromthe same caliber and using the same elements to the greatest extentpossible.

To this end. in the mechanical watch movement according to the presentinvention. the minute-wheel pinion is thicker than the minute-wheel, andthe minutewheel is driven onto the teeth of the minute-wheel pinion.

Two embodiments of the invention will now be de scribed by way ofexample with reference to the accompanying drawings. in which:

FIG. 1 is a partial axial section of the first embodiment.

FIG. 2 is a partial top plan view on a larger scale of the minutewheeland pinion of the movement shown in FIG. 1.

FIG. 3 is a partial section analogous to that of FIG. 1. showing thesecond embodiment, and

FIG. 4 is a top plan view of the hounwheel and the minute-wheel andpinion in the second embodiment The movement partially illustrated inFIG. I is of simplified construction. It comprises a frame consisting ofa hase-plate l. a wheel-train bridge 2, and a balance cock (not shown).these various elements being fus tened to one another by pillars. suchas pillar 3, riveted to the base-plate 1 and to one of the bridges. Amainspring is fitted in a harreLdrum 4 situated between the bridge 2 andthe baseplate l and mounted on a detachable arbor 5 which is axiallyfastened by a bolt 6 mak ing it axially integral with the hub of thedrum 4. Extending between the bridge 2 and the drum 4 is a ratchet-wheel7 integral with a sleeve 8 which is situated in side the drum 4 andserves to hook the inner end of the mainspring. The arbor 5 pivots in anopening in the bridge 2 and a corresponding opening in the base-plate I.It projects into a recess 9 in the outer face of the base-plate l and isprovided with a square 10 at the end of it. Engaged on the square 10 isa non-circular central opening of a minute-wheeLand-pinion assembly llwhich is fitted in the recess 9 and which rotates with the barrel-drum4. The minute-wheel 12 of this assembly 11 meshes with a cannon-pinion13. while its minute wheel pinion l4 meshes with an hour-wheel l5coaxial with the cannon-pinion 13. The cannon-pinion 13 is mounted on aninner pipe 16 integral with the baseplate I. The Cannon'pinion pipeproper and the pipe of the hour-wheel 15 pass through a central openingin a dial (not shown) and bear a minute-hand and an hourhand.respectively. at their ends. The movement described further comprises afourth-wheel-and-secondpinion assembly 17. the arbor of which is engagedin the inner pipe 16; this assembly 17 forms part of the wheel-trainconnecting the barrel-drum 4 to an escapement (not shown). It will henoted that the ratchetwheel 7 is blocked by a click l8 actuated by aspring (not shown) and pivoting on a cylindrical bearing surface of thepillar 3.

Since the arbor S rotates with the barrel 4 and drives theminute-wheel-and-pinion assembly 1], the gear ratios between the wheel12 and the cannon-pinion 13 on the one hand. and between the pinion l4and the wheel 15 on the other hand, must be such that the cannonpinion13 rotates at the rate of one revolution per hour. while the wheel 15rotates at the rate of one revolution every twelve hours. Moreover. forreasons which will become apparent later on. the speed of rotationselected for the barrel 4 is one revolution every 4 hours. As a result,the gearratio between the wheel 12 and the cannon-pinion 13 is 4:1.while the reduction-ration between the pinion 14 and the wheel 15 is1:3.

The structural details of the minutc-wheel-andpinion assembly 11 areshown in FIG. 2. The pinion 14 has a peripheral toothing made up of 12teeth 19. the tracing of which is visible in FIG. 2. This tracing isthat ofa standard toothing, the teeth of which are cut off atapproximately half their height by lateral faces 20 in the form ofportions of a cylindrical surface coaxial with the pinion 14. Thus allthe teeth 19 are cut off at the same height. and the lateral faces 20define an imaginary cylindrical surface which constitutes the envelopeof the pinion I4. The wheel 12 has a circular central opening 21. thediameter of which is the same as that of the imaginary cylindricalsurface defined by the lateral faces 20. The wheel I2 is driven directlyonto the teeth I) and extends between the middle of the thickness of thepinion I4 and one of its frontal faces, so that the truncated teeth I9are free for approximately half the thickness of the pinion I4. Thehour-wheel has a lib-tooth toothing 22 with a normal tracing and amodule equal to that of the toothing I9. These standard-profile teethmesh with the teeth I) even though the latter are truncated atmid-height, as may be seen in FIG. 2, so that the pinion describeddrives the wheel I5. which rotates continuously, completing onerevolution every l2 hours.

The assembly I1 is completely sunk into the recess 9. On the other hand,the wheel 12 is engaged with a scttingwheel (not shown) which cooperateswith the other members of the setting mechanism and which likewisepivots on the outer face of the baseplate I.

The minutc-wheel and pinion may be dismantled very easily, and afterthey have been removed, it is possible to extract the arbor 5 bygrasping it by a projecting head 23, which enables the barrel to betaken out laterally.

The second embodiment, shown in FIGS. 3 and 4, is based on an identicalcaliber to that of FIG. 1. Thus FIG. 3 again shows the base-plate l withits recess 9 and the barreLarbor 5. These elements, as well as thebridge 2. the barrel 4, and the elements of the wheel train, are alsoidentical. The barrel 4 and the arbor 5 likewise rotate at a speed ofone revolution every four hours.

A minutewheel-and-pinion assembly 24 is composed here of a toothed disc,identical to that of the first embodiment and accordingly designated bythe reference numeral 12, and a pinion 25 of a slightly differentdesign. This pinion 25 is of the same thickness as the pinion 14, andits central opening is likewise of the same size and shape. However, itstoothing differs in that it comprises eight teeth 26 identical to theteeth 19, i.e., laterally limited by lateral faces in the form ofcylindrical portions coaxial with the pinion, and four teeth 27 which,as may be seen in FIG. 3, have a lateral face 28, in the form of aportion of a cylindrical surface of the same diameter as the faces 20,for about half of their thickness. However, as these faces 28 take uponly half the thickness of the pinion 25, the four teeth 27, each havinga point 27a, project beyond the imaginary cylindrical surface limited bythe faces 20 and 28. These four points 27a gave have a normal toothprofile. They are positioned at 90 from one another around the axis ofthe pinion 25.

Whereas the wheel 12 driven onto the faces 20 and 28 of the pinionmeshes with a cannon-pinion 33, the toothing of which is identical tothat of the cannonpinion 13, the points 27a of the pinion 25 cooperatewith an hour-wheel 29 which is designed differently from wheel 15. Aswill be seen in FIG. 4. there is at the periphery ofthc wheel 29 atoothing made up of [2 triangular tecth 30. These teeth 30 cooperatewith a jumper 31 mounted in the recess 9 of the base-plate I. Thisjumper 31 normally holds the wheel 29 in a fixed position. The diameterof the circle defined by the apexes of the teeth 30 is such that thewheel 29 can rotate freely without coming into contact with the teeth 26of the pinion 25 but is caught by the points 27a of LII the teeth 27. Onthe other hand, the dimensions are such that each point 271: candisplace the wheel 29 by an angle sufficient for the apex 32 of thepoint of the jumper 31 to pass over the apex of one of the teeth 30.Starting from this position, the resiliency of the jumper 3| advancesthe wheel 29 to the position shown by the dash-line in FIG. 4, where thetwo flanks ofthc jumper 31 are simultaneously in contact with two of theteeth 30. Via its points 27a, therefore, the pinion 25 ad vances thehounwheel 29 by jumps of one twelfth of a revolution every time thepinion 25 rotates In this embodiment, the pipes (not shown) of thecannon-pinion 33 and of the wheel 29 will be shorter than in the firstembodiment, and they carry a minutedisc and an hour-disc (not shown),respectively. These discs will be situated between the base-plate l andthe dial (not shown), and the minute' and hour-indications printed alongthe peripheries ofthe discs will appear in an aperture in the dial. Inthis embodiment. the fourth wheel-and-second-pinion assembly 17 will notcomprise any pivot intended to receive the seconds-hand. and the dialneed not have a central opening.

As a variation of the embodiment according to FIGS. 3 and 4, the teeth27 might also be full for their entire thickness. In that case, thecentral opening of the disc 12 will be blanked with notchescorresponding to the teeth 27 so that this disc can be driven onto thepinion.

Whereas the pinion 14 can be made either by blanking from a circulardisc or by milling a standard toothing at the periphery of the disc,then lathe-turning the teeth to the diameter defined by the faces 20,the pinion 25 will preferably ba made by milling the teeth 26 and 27,then lathe turning the lateral faces 28 and the lateral faces 20 to athickness corresponding to that of the faces 28, the piece in which theteeth 26 and 27 are milled being initially blanked so that the teeth 26are truncated as shown in FIG. 4.

It has been found that minute'wheels and pinions such as those describedabove, and particularly such as the assembly 24, of simplifiedconstruction, drive the cannon-pinion and the hour-wheel underconditions corresponding to conventional conditions. In particular,despite the fact that the teeth of the pinion 14 are truncated forapproximately half their height, an hourwheel with a conventionaltoothing, such as wheel I5, meshes perfectly with them. In theembodiment having a jumping hour-wheel, since the distance between theaxes of the barrel and the cannon-pinion is the same as in the caliberwith continuous drive of the wheel [5. the star 29 will have a slightlysmaller diameter than the wheel 15. Moreover, it will have onlyone-third as many teeth.

What is claimed is:

I. A mechanical watch movement comprising:

a minute-wheel pinion having a plurality of teeth each having a lateralface portion in the form of a cylinderical arc coaxial with saidminute-wheel pinion, at least some of said teeth having a furthersubstantially pointed portion which extends from and beyond said arcuateface portion;

a toothed minute-wheel having a thickness which is less than thethickness of said minute-wheel pinion and fixed to said arcuate lateralface portions of said minute-wheel pinion;

a cannon-pinion having teeth which mesh with said toothed minute-wheel;and

3. A watch movement in accordance with claim I, wherein saidminute-wheel is coupled to a barrel-drum.

4. A watch movement in accordance with claim 3.

wherein said minutewheel is situated on the outer face of a baseplate ofthe movement.

5. A watch movement in accordance with claim 4, wherein saidminute-wheel is fitted in a recess in said haseplate.

1. A mechanical watch movement comprising: a minute-wheel pinion havinga plurality of teeth each having a lateral face portion in the form of acylinderical arc coaxial with said minute-wheel pinion, at least some ofsaid teeth having a further substantially pointed portion which extendsfrom and beyond said arcuate face portion; a toothed minute-wheel havinga thickness which is less than the thickness of said minute-wheel pinionand fixed to said arcuate lateral face portions of said minute-wheelpinion; a cannon-pinion having teeth which mesh with said toothedminute-wheel; and a toothed hour-wheel coaxial with said cannon-pinionand having an outside diameter such that only said pointed portions ofsaid minute-wheel pinion engage said toothed hour-wheel.
 2. A watchmovement in accordance with claim 1, wherein the hour-wheel is normallyheld in a fixed position by a jumper acting upon its toothing, and saidpointed portions are so disposed that the hour-wheel is driven in jumpsof one unit of circular pitch of its toothing by each point of theminute-wheel pinion.
 3. A watch movement in accordance with claim 1,wherein said minute-wheel is coupled to a barrel-drum.
 4. A watchmovement in accordance with claim 3, wherein said minute-wheel issituated on the outer face of a baseplate of the movement.
 5. A watchmovement in accordance with claim 4, wherein said minute-wheel is fittedin a recess in said baseplate.